I am sure that there are similar schematics floating around the web and some people might have posted them here already, but I drew this up for myself and figured I would share it just in case someone else could use it.

The source sqaurewave could come from anything, but in my schematic it is a 40106 oscillator. It runs a little high and is used as the clock frequency for the shift register. The same signal is also divided with a 4040 and used as the base input for the shift register. I do this dividing so that the spacing of the steps changes along with the pitch.

I added a couple of option at the output for more shaping. A cap to ground rounds it off into a nice sine wave. Passing the sound through a low value cap acts as a highpass filter that turns each edge of the step into a spike.

You could probably do some really weird wave shaping by using separate low or highpass filters on each output from the 4006. This might almost allow you to draw the desired waveform with a bit of practice.

Sodium - It might work with other waveforms if the peaks go over the CMOS threshold, but I think for optimal performance you will want to use a comparator to create a squarewave if you are using a different wave as the source.

Sonic - I was actually thinking about your vco when I was making it. It would be a cool module.

I was playing around with it today adding more or less of the shift register outputs, and changing the mixing resistors for diodes or small caps. You can make some very unique waveforms, but it is kind of difficult to predict how it is going to look and sound until you test it out._________________JacobWatters.com

I also just created a similar stepped saw wave. I will make the schematic and post in a couple of days, but it is just a 4017 that has a different valued resistor on each output. Q1 has low resistance, Q9 has a lot of resistance, and Q10 isn't connected.

Isn't it easier to get that saw wave from an R2R ladder and a 4040? Acctually probably about the same effort/parts are required for each._________________As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"

I've seen that once before used some different chips though if I remember rightly, you've come up with some good ideas here nevertheless I look forwards to hearing some of these circuits _________________As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"

Can I substitute different resistor values? 150k and 75k are odd values that i do not have in quantity.

Would 47k and 100k work?

The ratio is important: R/2R. 47K is half of 100K, minus 6%. With an error of 6%, your error term is as large as your fourth bit (1/16th == 0.0625, ~6%). That means that you may as well only build a three-bit R/2R ladder.

For an R2R ladder, unless you want to be precise and accurate, almost any value will work. I think I used resistors near 220k and 100k in my Lunetta death pipes from outer space. I didn't have enough you see? So I just put in any near values. Everything still worked fine, things were just a bit non-linear._________________As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"

sometimes accurate and precise is either difficult to achieve, or just not as interesting. anyway, the ladder-shaped thing can be used to do all kinds of interesting translations of information._________________http://soundcloud.com/douglasmseidel

Nice info . I approach the lunetta as a free form type of instrument, therefore precision isn't so important to me. I've done many versions of wave shapers, filters, adsr's, vco's and some of their complexity rivals that of modulars. Those machines rely on precise tolerances and ain't what I'm looking for in lunetta building.

Mosc clued many of us "in" long ago in reiterating the importance of keeping it simple with these circuits. Go ahead and make complicated modules but keep in mind they may not work the way you hoped. That is the Tao of Lunetta

But by all means experiment; us ol timers enjoy the newly initiated and their zeal ._________________Zontar Prevails!

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